Background: Coughing is an important protective mechanism for cleaning airways from fluids and foreign substances. Life-threatening situations may emerge when coughing loses its efficiency due to muscular weakness or impaired mucociliary function. Objective: This study aimed to investigate how a cough assist device affects hemodynamic monitoring and oxygen (O₂) saturation in children using mechanical ventilation (MV). Patients and methods: Fifty children who had pneumonia and receiving MV, from both gender with age ranged from 4 to 9 years old, were included in this research study. The children were divided into two equal groups using a random way: The intervention group received both a cough assist device and conventional chest physiotherapy, while the control group received only conventional chest physiotherapy. Results: Compared to the control group, the intervention group had a substantial reduction (p < 0.05) in respiratory rate (RR) and a significant rise (p < 0.01) in O₂, VTe, and Cdyn following treatment. Conclusion: Children on MV had improved respiratory parameters, oxygen saturation, and chest condition when a cough assist device was used combined with conventional chest physical therapy.